Foams are typically produced by the mixing of a chemical, water and a gas under certain conditions. The particular chemicals employed depends upon the desired use of the foam. For example, in the agricultural arena foams are often used to apply pesticides and are often preferable to liquid application.
The application of chemicals in a foamed condition offers a number of benefits. The foam application permits the chemicals to be used with lower supply rates and active chemical content, thereby reducing costs. Further, the use of a foam composition reduces health and safety hazards caused by the splashing or drift of tiny droplets or a fine mist. Because a foam is readily visible it also provides a convenient way for visually determining coverage.
Generally, two basic methods have been utilized to generate foams. One method is the use of a chemical foaming agent which is added to the solution, and the solution is then foamed. The other method is the introduction of gas such as air into the liquid to form minute bubbles, thereby collectively forming the foam. The application of agricultural chemicals by foam generating equipment traditionally includes a nozzle unit which mixes air with liquid chemicals.
The type and consistency of foam created by particular foam generating nozzles is a function of a number of factors, including the chemicals to be applied, the pressure of the material when applied to the nozzle unit and the design of the nozzle unit. A resulting consistency of the foam is often dictated by the anticipated application. That is, for applications requiring prolonged retention on a vertical or downward facing surface, it is usually desirable to apply the material as a thick foam. Such foams often follow a 1:10 ratio, that is for each unit volume of liquid, 10 unit volumes of foam are produced. Alternatively, if penetration of a porous surface is desired, the foam is preferably formed with a minimally sized bubbles in a ratio of approximately 1:2.
It has been found that at the relatively low operating pressures, it is difficult to obtain sufficiently small particle size and hence sprayable foam generation. Therefore, prior systems have relied upon relatively high fluid pressures for foam generation. The prior foam generating devices are relatively high pressure units requiring 40 psi or more. The mechanisms required to generate these relatively high pressures and the inability of the foaming nozzles to efficiently use the available energy at low pressures have prevented relatively low pressure foaming technology in a truly portable, human transportable foaming apparatus.
Further, in view of the relatively complicated structure required for the passage of a liquid, introduction of air, generation of foam and application of the foam, a given foaming nozzle unit traditionally creates only a single type foam. That is, if alternative chemical compositions, or application patterns are desired, the nozzle unit must be completely removed and an entirely new nozzle unit applied. This increases the cost of the foam applicators.
Therefore, a need exists for a foaming nozzle assembly which is easily reconfigured to create a variety of foams. Further, the need exists for a foam generating nozzle which may be readily disassembled, cleaned and reassembled. The need also exists for such a nozzle assembly which may be reconfigured with interchangeable components. A further need exists for a foam generating nozzle that can be used in relatively low pressure applications, such as less than approximately 35 psi and still generate sufficient quantities of foam.